Gas blast wiping collar for cleaning pipettes

ABSTRACT

A system for cleaning a pipette includes a gas dispensing means attached to the pipette and defining an orifice for directing gas onto the pipette surface. By controlling the application of gas through the dispensing means, the pipette surface can be maintained free of liquid thereby avoiding inaccurate testing while also avoiding possible contamination of the pipette.

iinite States Patent 1191 11] 3,842,689 Vollick et a1. Qct. 22, 1974 [54] GAS BLAST WIPING COLLAR FOR 2,194,565 3/1940 Moss 134/37 x 2,604,895 7/1952 Fechter 134/170 X CLEANING PIPETTES 2,737,957 3/1956 Thaxton 15/404 X Inventors: Carlisle Vollick; Stanley J- 2,826,209 3/1958 Klein etal. 134/170 Williams, both of London, Ontario, 3,552,212 1/1971 Ohlin 15/306 R X Canada 3,620,813 11/1971 Minbiole, Jr. et a1. 134/34 X [73] Assignee: Bach-Simpson Limited, Ontario,

Canada Primary Examiner-S. Leon Bashore Assistant Examiner-Richard V. Fisher [22] Filed' 1972 Attorney, Agent, or Firm-McDougall, Hersh 84 Scott [21] Appl. No.: 278,977

[52] US. Cl. 73/425.4 P, 15/316 R, 15/404, ABSTRACT 23/259, 134/37 51 1m. (:1 BOll 3/02, B08b 5/02 A System for cleanmg a Wette Includes a gas 5 Field of Search 34/37 34 1 C, 1 7 C ing means attached 110 the pipette and defining an 01'1- 134/168 C 169 73/4254 9; 15/1O4'04 fice for directing gas onto the pipette surface. By con- 404 405 A 3 306 R 316 R 316 trolling the application of gas through the dispensing 312 23/259 means, the pipette surface can be maintained free of liquid thereby avoiding inaccurate testing while also [56] References Cited avoiding possible contamination of the pipette.

UNITED STATES PATENTS 5 Claims, 4 Drawing Figures 1,628,530 5/1927 Burnett 15/404 X PULSED AIR JET PMENTEB BUZZER 3, 842,580

PbLsED AI'R JET x GAS BLAST WIPING COLLAR FOR CLEANING PIPETTES This invention relates to pipette constructions. In particular, the invention is directed to the use of pipettes for obtaining samples of liquids in accurately measured amounts.

In various testing operations, for example, in the analysis of blood and urine samples, it is often necessary to obtain accurately measured liquid portions. In the testing referred to, it is also often necessary to dilute the samples to fixed and known values.

Scientific instruments are available for accomplishing the operations referred to. Commercial diluters, for example, of the type manufactured by Hobbs Scientific, Inc. provide an example of the type of instruments useful for applications of the type referred to. In such constructions, a pipette is employed for drawing a sample which is mixed with a diluent and then delivered by the pipette as a diluted sample.

In the course of such operations, the pipette, and in particular the external surfaces thereof, are in contact with liquid. This liquid tends to cling to the pipette surfaces, and must be removed so that the liquid will not enter into the measured samples and thereby destroy the accuracy of amounts handled or of the diluent ratio. Typically, the exterior surfaces of pipettes are cleaned by wiping liquid particles with a tissue; however, this leads to certain problemsSpecifically, incomplete wiping will result in a contaminated solution. Furthermore, the presence of a tissue at the end of a pipette can readily draw off a portion of a sample which affects the diluent ratio. Since a typical sample drawn into a pipette may be only 50 microliters, even very small disruptions of the liquid amounts can lead to major errors.

It is an object of this invention to provide an improved system for the handling of samples through the use of pipettes.

It is a more specific object of this invention to provide an improved cleaning arrangement for pipettes whereby complete and reliable cleaning can be accomplished with great efficiency.

These and other objects of this invention will appear hereinafter and for purposes of illustration, but not of limitation, specific embodiments of the invention are shown in the accompanying drawings in which:

FIG. 1 is an illustration of a pipette construction associated with liquid cleaning means of the type contemplated by this invention;

FIG. 2 is an enlarged cross-sectional view of the cleaning means in association with a pipette;

FIG. 3 is a horizontal sectional view taken about the line 3-3 of FIG. 2; and,

FIG. 4 is a horizontal sectional view illustrating the alternative form of the invention.

This invention relates to a method and means for use in conjunction with pipettes being employed for handling liquid samples. In particular, the invention is concerned with means for cleaning the exterior surfaces of the pipette after exposure of the pipette to liquid.

The structure of the invention comprises a collar structure which is fit onto a pipette body. The collar includes a dispensing opening and a source of fluid, for example air, is connected to the collar. In use, the fluid is dispensed onto the pipette surfaces for removal of any liquid thereon thus insuring accurate sampling and minimizing the possibility of contamination. The collar orifice is preferably adjustable, and the fluid source is preferably provided with pulsating means whereby various conditions of operation can be achieved.

The accompanying drawings illustrate a pipette 10 which is maintained in a suitable receptable 11. This receptacle may be a part of a diluter of the type previously referred to. In the use of such structures, the pipette surfaces are brought into contact with liquid during drawing ofa sample and during delivery of a diluted sample.

An air dispensing structure 12 is employed in conjunction with the pipette 10. This dispensing structure comprises a collar formed of a first tubular member 14 and a second tublar member 16. The internal diameter of the member 14 approximates the external diameter of the pipette whereby the member 14 can be conveniently held or attached in position on the pipette body.

The member 14 is externally threaded for receipt within the threaded bore of the member 16. An annular fluid channel 18 is defined between the surfaces of the members 14 and 16, this channel terminating in a dispensing opening 20. The dimensions of the channel 18 can be varied by rotating the member 14 so that some control is provided for the dispensing of fluid.

A hollow tube 22 is fit within an opening defined by the member 16. This tube thus serves to deliver air or other fluid for movement of the air through the passage 18 and out of the opening 20. The tube 22 is connected to a source 24 of pulsating air. This air supply means may be of any conventional type resulting in the application of bursts of fluid onto the pipette surfaces.

FIG. 4 illustrates a modified version of the invention. In this instance, the air dispensing structure comprises an outer tubular member 28 defining a passage 30 which receives the end of tube 32. The inner tubular member 34 fits around pipette 36 in the manner previously described.

The introduction of air through the tube 32 results in a swirling action of the air relative to the pipette surface. This provides a highly effective alternative means for cleaning the surface.

In the use of a pipette of the type described, the tip 26 is immersed in a liquid sample, and liquid is drawn into the pipette body. When the proper amount of a sample has been drawn, the pipette is removed from the sample, and the cleaning mechanism of the invention is operated. By providing short bursts of air, it has been found that the exterior pipette surfaces become dry very quickly. This is accomplished without any contact with the surfaces, for example, by means of a tissue. Without this contact, there is no danger of contamination by any portions of the tissue or by any other substance. In addition, contact by a tissue at the outlet end of the tip 26 can result in the premature discharge of at least some liquid contents of the pipette. With the arrangement of this invention, that problem is completely eliminated.

In the event that the air is being dispensed in amounts which are too small or too large to achieve the desired results, the member 14 can be readily turned to increase or decrease the size of the passage 18. Such variations are particularly desirable when different types of liquids are to be handled.

After a sample has been drawn and diluted, the pipette is again utilized for delivering the diluted sample to a desired container. Once this has been accomplished, the cleaning mechanism can again be employed to eliminate any residue which might be present on the body of the pipette.

it will be understood that various changes may be made in the above description which provide the characteristics of the invention without departing from the spirit thereof.

That which is claimed is:

1. In a pipette construction wherein the pipette is immersed in a liquid during use, the improvement in means for cleaning the pipette comprising a gas dispensing means attached to the pipette, means for supplying gas to said dispensing means, said dispensing means comprising a member attached to the body of the pipette in a position spaced from the end of the pipette through which liquid passes into and out of the pipette, said member comprising a first tubular portion defining a central passage approximating the exterior configuration of said pipette, said first tubular portion being attached onto said pipette for maintaining the tubular portion in spaced relationship relative to the end of the pipette, and a second tubular portion threaded onto said first tubular portion thereby forming an orifice surrounding the pipette body and opening in a direction toward said end of the pipette, and including means for adjusting the size of said orifice, said orifice being defined between the tubular portions and being adjustable upon relative rotation of the tubular portions, and operation of said dispensing means applying a gas stream through the orifice to the exterior surface of said pipette thereby removing liquid particles from the pipette surface.

2. A construction in accordance with claim 1 wherein said end of the pipette comprises a small diameter portion with the pipette body tapering outwardly away from said end to a juncture with a large diameter portion which comprises said exterior configuration of the pipette. 3. A construction in accordance with claim 1 wherein said gas comprises air, and means connected to said gas supplying means for intermittently supplying air to said dispensing means.

4. A construction in accordance with claim 1 wherein the means for supplying gas to said dispensing means comprise an air tube connected to said dispensing means, said air tube directing air radially inwardly toward said first tubular portion.

5. A construction in accordance with claim 1 wherein the means for supplying gas to said dispensing means comprise an air tube, said tube directing gas tangentially relative to the axis of said pipette. 

1. In a pipette construction wherein the pipette is immersed in a liquid during use, the improvement in means for cleaning the pipette comprising a gas dispensing means attached to the pipette, means for supplying gas to said dispensing means, said dispensing means comprising a member attached to the body of the pipette in a position spaced from the end of the pipette through which liquid passes into and out of the pipette, said member comprising a first tubular portion defining a central passage approximating the exterior configuration of said pipette, said first tubular portion being attached onto said pipette for maintaining the tubular portion in spaced relationship relative to the end of the pipette, and a second tubular portion threaded onto said first tubular portion thereby forming an orifice surrounding the pipette body and opening in a direction toward said end of the pipette, and including means for adjusting the size of said orifice, said orifice being defined between the tubular portions and being adjustable upon relative rotation of the tubular portions, and operation of said dispensing means applying a gas stream through the orifice to the exterior surface of said pipette thereby removing liquid particles from the pipette surface.
 2. A construction in accordance with claim 1 wherein said end of the pipette comprises a small diameter portion with the pipette body tapering outwardly away from said end to a juncture with a large diameter portion which comprises said exterior configuration of the pipette.
 3. A construction in accordance with claim 1 wherein said gas comprises air, and means connected to said gas supplying means for intermittently supplying air to said dispensing means.
 4. A construction in accordance with claim 1 wherein the means for supplying gas to said dispensing means comprise an air tube connected to said dispensing means, said air tube directing air radially inwardly toward said first tubular portion.
 5. A construction in accordance with claim 1 wherein the means for supplying gas to said dispensing means comprise an air tube, said tube directing gas tangentially relative to the axis of said pipette. 